Field
The embodiment relates to a solar cell.
Background
A method of manufacturing a solar cell for solar light power generation is as follows. First, after preparing a substrate, a rear electrode layer is formed on the substrate and patterned by a laser, thereby forming a plurality of rear electrodes.
Then, an optical absorption layer, a buffer layer, and a high resistance buffer layer are sequentially formed on the rear electrodes. The optical absorption layer can be formed by extensively using various schemes including a scheme of forming a Cu(In, Ga)Se2 (CIGS) based-optical absorption layer by simultaneously or separately evaporating copper (Cu), indium (In), gallium (Ga), and selenium (Se) and a scheme of performing a selenization process after forming a metallic precursor. The energy band gap of the optical absorption layer is in the range of about 1 eV to about 1.8 eV.
Then, the buffer layer including cadmium sulfide (CdS) is formed on the optical absorption layer through the sputtering process. The energy band gap of the buffer layer is in the range of about 2.2 eV to about 2.4 eV. Thereafter, the high resistance buffer layer including zinc oxide (ZnO) is formed on the buffer layer. The energy band gap of the high resistance buffer layer is in the range of about 3.1 eV to about 3.3 eV.
Next, groove patterns may be formed in the optical absorption layer, the buffer layer, and the high resistance buffer layer.
Then, a transparent conductive material is deposited on the high resistance buffer layer and the transparent conductive material is filled in the groove pattern. Thus, a transparent electrode layer is formed on the high resistance buffer layer and connection wires are formed inside the groove patterns, respectively. For example, a material used for the transparent conductive layer and the connection wires may include aluminum (Al) doped zinc oxide. The energy band gap of the transparent electrode layer is in the range of about 3.1 eV to 3.3 eV.
After that, the groove pattern is formed in the transparent electrode layer, thereby forming a plurality of solar cells. The transparent electrodes and the high resistance buffers correspond to cells, respectively. The transparent electrodes and the high resistance buffers may be arranged in the form of a stripe or a matrix.
The transparent electrodes are misaligned with the rear electrodes and the transparent electrodes are electrically connected with the rear electrodes through the connection wires, respectively. Therefore, a plurality of solar cells can be electrically connected with each other in series.
Meanwhile, the optical absorption layer is formed on the rear electrode layer. In detail, the optical absorption layer is formed on the patterned rear electrode layer.
However, the optical absorption layer may be delaminated after being deposited because a bonding strength is weak on a boundary surface between the optical absorption layer and the rear electrode layer, or between the optical absorption layer and the support substrate exposed through the patterning. The delamination of the optical absorption layer may increase the overall electrical resistance of the solar cell, so that the overall efficiency of the solar cell may be degraded.
Accordingly, there is required a solar cell having a novel structure capable of preventing the optical absorption layer from being delaminated.